CN104181262B - The small boiler case of a kind of cold area free low-power consumption - Google Patents

Abstract

The present invention relates to the small-sized chromatogram stove case of a kind of cold area free low-power consumption, capillary chromatographic column is around on thin shell type metal cylinder outside surface, cartridge heater inwall posts heating film or is wound with heating of metal silk, makes thin shell type metal cylinder become heating samming cylinder, is called for short cartridge heater.The front and back tank wall perforate of holding furnace case, cartridge heater inner space is communicated with the external world, and the outside of former and later two xsect edges of cartridge heater and whole cartridge heater is all thermally sealed on the inside of holding furnace case.The top of stove case is provided with chromatic spectrum sample feeder and detecting device, and all by heated constant temperature to design temperature.The inlet end of chromatographic column is connected to injector, and endpiece is connected to detecting device.The major part of capillary chromatographic column because of on cartridge heater outside surface with cartridge heater equality of temperature.This small boiler case is also applicable to being elder generation with low-power consumption and temperature-controlled precision requires higher occasion.

Description

A small furnace box with no cold zone and low power consumption

technical field

The invention relates to the technical field of gas chromatographs, in particular to a small chromatographic column oven box without a cold zone and low power consumption, which is used for desktop chromatographs and portable chromatographs.

Background technique

Gas chromatography is widely used in food safety testing, environmental pollution testing, petrochemical analysis, drug and natural product analysis, flavor and fragrance analysis, wine production quality control analysis, cigarette production quality control analysis, and clinical sample analysis, etc. With the development of society, more and more emphasis is placed on energy saving, rapid analysis and on-site analysis.

The traditional gas chromatograph consumes a lot of power, mainly in the oven heating of the chromatographic column. During the heating process of the chromatograph, the maximum power consumption can reach 2KW. At present, the number of gas chromatographs in my country has exceeded 80,000, almost all of which are traditional, so the total power consumption is also quite high.

At home and abroad, efforts have been made to reduce the power consumption of gas chromatographs, especially in the development of fast chromatography and portable gas chromatographs, and a variety of methods and technologies for reducing power consumption have been developed. However, the low-power chromatographic column heating and uniform temperature technology that can achieve temperature-programmed operation so far has encountered a common problem: the temperature at the leading end of the capillary chromatographic column leaves the main body of the chromatographic column without an auxiliary heating device, causing the temperature at the leading end to be lower than that of the chromatographic column. The temperature of the main body of the column is called the cold end in technical terms, and the space away from the main body of the column is called the cold zone. The cold end phenomenon causes the broadening of the chromatographic peaks and the decrease of the separation ability, resulting in the decrease of the detection performance.

In order to solve this problem, the latest foreign commercial instruments adopt the method of putting the low-power chromatographic column heating components into a furnace with internal circulation fan and auxiliary heating to eliminate the cold zone, so that the leading end of the chromatographic column can be miniaturized Additional heating of the chromatography oven. This method requires that the temperature control of the small oven be synchronized with the heating rate and temperature value of the chromatographic column, so as to avoid the temperature change of the heating chamber from interfering with the temperature change of the chromatographic column heating system. Therefore, this system not only has complex control, high precision requirements, and high cost, but also has a peak power consumption of 800-1200W, which offsets the important advantages of the low-power chromatographic column heating system.

Therefore, how to provide a chromatographic column heating uniform temperature system with no cold zone and low power consumption, and at the same time meet the requirements of using ordinary capillary chromatographic columns, users can replace chromatographic columns, simple operation, simple manufacture, and low cost of use, is a technology in the art. Technical problems that people need to solve.

Contents of the invention

The purpose of the present invention is to provide a technical solution of a small furnace box with no cold zone and low power consumption, which is used for uniform temperature heating of the chromatographic column with low power consumption and elimination of the cold zone.

In the present invention, the space formed between the outer surface of the heating cylinder and the inner chamber of the heat preservation furnace is used as the heat preservation area of the leading end of the chromatographic column. The capillary chromatographic column is tightly wound on the outer wall of the heating cylinder, and the electric heating mold is pasted on the inner wall of the heating cylinder. The thermal radiation generated by the relatively high temperature of the chromatographic injector and detector is used to heat the leading end of the capillary column below it, supplemented by the heat conduction heat transfer of the carrier gas of the chromatographic column and the heat radiation when the heating cylinder is heated up, so as to ensure the temperature of the leading end of the chromatographic column Always higher than the temperature of the column body.

The two ends of the heating cylinder are in close contact with the front and rear inner walls of the incubator, and holes are opened at the corresponding positions of the wall of the incubator and the inner cavity of the heating cylinder, so that the outside world is directly connected with the inner cavity of the heating cylinder, but not connected with the inner chamber of the incubator;

The cooling fan is fixed on the outside of the incubator at a position corresponding to the hole in the inner chamber of the heating cylinder. The heating cylinder can be forced air cooled.

Three thermistors are respectively fixed on the outer surface of the heating cylinder and the heating blocks of the chromatographic sample injector and the detector, and are connected with the temperature controller. The temperature controller controls the temperature of the heating cylinder, the chromatographic sampler and the chromatographic detector respectively.

Preferably, the metal part of the chromatographic sample injector and detector exposed on the top of the furnace can effectively radiate heat to the outlet end of the capillary column without excessively affecting the corresponding part of the chromatographic column main body. The axial distance L between the detectors is set as L=D+d1/2+d2/2, where D is the diameter of the heating cylinder, and d1 and d2 are the diameters of the metal parts of the injector and detector exposed on the top of the furnace, respectively.

Preferably, the heat capacity of the furnace chamber of the small furnace box is as low as possible, so that the temperature of the furnace chamber can quickly follow the temperature rise or fall of the heating cylinder, but it is always at a slightly higher temperature than the heating cylinder. Among the six surfaces of the inner wall of the insulated furnace box, except for the upper part where the chromatographic sampler and detector are installed, the other five surfaces are not covered with metal sheets, or partially covered with metal sheets with a thickness of ≤0.3 mm. Sheet metal covering.

The present invention has the following advantages:

1. Without using the auxiliary heating system, the function of no cold zone at the leading end of the chromatographic column is realized, which greatly simplifies the structural design of the chromatographic oven and the temperature following control system for different heating temperature zones. Significantly reduce costs;

2. The inside of the heating uniform temperature cylinder of the chromatographic column communicates with the outside world, and has certain convection heat dissipation, so the temperature balance is very fast. When cooling down, turn on the fan located outside the furnace box to force convection to dissipate heat, and because the heat capacity of the heating cylinder is very low, the cooling speed is very fast, up to 60°C/min or even faster;

3. Because the heat radiation and heat conduction of the heating objects in the furnace are used to heat the lead-out end of the chromatographic column, the enhanced furnace insulation design can be adopted without reducing the performance of the rapid heat balance of the chromatographic column. Save electricity consumption due to energy saving. In order to quickly balance the temperature of the traditional chromatographic furnace, the overall thermal insulation performance of the furnace is deliberately designed to ensure the heat dissipation capacity, so the heating power consumption is high.

Description of drawings

Fig. 1 is the front view of a kind of invented small furnace box device without cold zone.

Fig. 2 is a three-dimensional schematic diagram of a small furnace box device without a cold zone of the present invention.

Among the figure: 100-heating cylinder; 101-heating film; 102-cooling fan; 110-capillary chromatographic column; 121-chromatographic sampler; 122-chromatographic detector; 200-incubator; - the front wall of the incubator; 211 - the air hole on the front wall; 220 - the rear wall of the incubator; 221 - the air hole on the back wall; 300 - the temperature controller; 310 - the thermistor.

Fig. 3 is the spectrogram of polycyclic aromatic hydrocarbon standard sample analysis with the invented small furnace box and chromatographic column uniform temperature heating device. In the figure, 1-naphthalene, 2-acenaphthene, 3-phenanthrene, 4-anthracene, 5-fluoranthene, 6-pyrene.

Fig. 4 is to use the inventive small furnace box and chromatographic column homogeneous heating device to be used for various mixed standard sample analysis spectrograms.

In the figure: 1, methanol, acetaldehyde; 2, ethanol; 3, acetone; 4, dichloromethane; 5, n-hexane; 6, chloroform; 7, furan; 8, dichloroethane; 9, benzene; 10, n-butanol; 11, ethylene glycol, trichlorethylene, heptane 12, toluene; 13, octane; 14, ethylbenzene, o-xylene; 15, m-xylene; 16, p-xylene; 17, nonane 18. Decane.

detailed description

The invention relates to a small chromatographic furnace box with no cold zone and low power consumption. Suitable for ovens in small gas chromatographs and separate column ovens in multidimensional chromatographs. The principle of the method is: the capillary chromatographic column is wound on the outer surface of a thin-shell metal cylinder, and the inner wall of the heating cylinder is pasted with a heating film or wound with a heating wire, so that the thin-shell metal cylinder becomes a heating uniform temperature cylinder, referred to as a heating cylinder. Holes are opened in the front and rear walls of the heat-retaining furnace box so that the inner space of the heating cylinder communicates with the outside world, while the front and rear cross-sectional edges of the heating cylinder and the entire outside of the heating cylinder are heat-sealed inside the heat-retaining furnace box. A chromatographic sample injector and a detector are installed on the top of the oven box, and both are heated to a set temperature. The inlet end of the column is connected to the injector, and the outlet end is connected to the detector. Utilize the heat conduction and heat radiation of the connecting parts between the injector and the detector and the chromatographic column to heat the chromatographic column in the connecting section. The main part of the capillary column is at the same temperature as the heating cylinder because it is wound on the outer surface of the heating cylinder. The heat balance of the furnace box is achieved by the natural heat dissipation and heat radiation of the heated parts in the furnace, the natural heat dissipation of the inner cavity of the heating cylinder communicated with the outside world, or the forced heat exchange and cooling of the outside air and the inner wall of the heating cylinder by the fan. This small furnace box is also suitable for occasions where low power consumption is the priority and high temperature control accuracy is required.

The present invention will be further described below in conjunction with accompanying drawings and embodiments.

Example 1

As shown in Figure 1, it is a schematic diagram of a small furnace box without a cold zone. The small furnace box without a cold zone is composed of a heating cylinder 100, a heating wire 101, a cooling fan 102, a capillary chromatographic column 110, and a chromatographic sample injector. 121, a detector 122, an incubator 200, a temperature controller 300 and a thermistor 301.

The external dimensions of the incubator 200 are length × width × height equal to 258mm × 103mm × 253mm, and the internal dimensions are length × width × height equal to 225mm × 70mm × 220mm. A composite felt made of glass fiber and silica aerosol particles wrapped in fiber cloth.

The heating cylinder 100 is an aluminum cylinder with a diameter of 120mm, a thickness of 0.6mm, and a height of 70mm; the heating wire 101 is a 38m copper enameled wire with a resistance value of 0.133Ω/m and a diameter of 0.4mm, which is wound on the inner wall of the heating cylinder 100 in a single layer; The capillary chromatographic column 110 is a quartz capillary tube of 30m×0.32mm×0.4mm, which is wound in a single layer on the outer surface of the heating cylinder 100, and the entire heating cylinder 100 is suspended and fixed at the middle lower position of the rear wall 220 of the furnace box (refer to Figure 1) , the edges of both ends of the heating cylinder 100 are in close contact with the inner walls of the front and rear walls 210 and 220 of the incubator 200, and the walls of the incubator 210 and 220 have holes 211 and 221 at the corresponding positions of the inner cavity of the heating cylinder, so that the outside world and the heating cylinder The inner cavity of 100 is directly connected, but not connected with the inner chamber 205 of the incubator;

The cooling fan 102 is fixed on the opening of the rear wall 220 of the incubator;

The chromatographic sampler 121 and the chromatographic detector 122 are installed on the top of the chromatographic furnace box, the inlet port 111 of the quartz capillary column is connected to the chromatographic sampler 121, and the outlet port 112 of the capillary column is connected to the chromatographic detector 122;

Three thermistors 310 are respectively fixed on the outer surface of the heating cartridge 100 and the heating blocks of the chromatography sampler 121 and the detector 122 , and are connected with the temperature controller 300 . The temperature controller controls the temperatures of the heating cylinder 100, the chromatographic sampler 121 and the chromatographic detector 122 respectively.

This embodiment is used to separate and analyze polycyclic aromatic hydrocarbon standard samples.

Samples: naphthalene, acenaphthene, phenanthrene, anthracene, fluoranthene, pyrene (sample concentration 200ppm)

Gas chromatography conditions:

Split/splitless inlet temperature 280°C; FID detector temperature 300°C; splitless injection, injection volume 1mL; 30m×0.32mm×0.4mm SE-30 quartz capillary column (Kefen, Dalian Kemei Precision Instrument Co., Ltd. Co., Ltd.), carrier gas type: H2, carrier gas flow rate: 2mL/min; temperature program: keep at 40°C for 2 minutes, rise to 140°C at a rate of 25°C/min, and then rise to 280°C at a rate of 10°C/min Keep it for 10min.

See Figure 3 for the spectrogram.

Application example 2:

As shown in Figure 1, it is a schematic diagram of a small furnace box without a cold zone. The small furnace box without a cold zone is composed of a heating cylinder 100, a heating wire 101, a cooling fan 102, a capillary chromatographic column 110, and a chromatographic sample injector. 121, a detector 122, an incubator 200, a temperature controller 300 and a thermistor 301.

The external dimensions of the incubator 200 are length × width × height equal to 258mm × 103mm × 253mm, and the internal dimensions are length × width × height equal to 225mm × 70mm × 220mm. Glass wool wrapped in fiber cloth.

The heating cylinder 100 is an aluminum cylinder with a diameter of 100mm, a thickness of 0.6mm, and a height of 70mm. The heating film 101 is attached to the inner wall of the heating cylinder 100. The capillary column 110 is a stainless steel capillary MXT-530m×0.25mm×0.5mm (Restek, USA). Wrap it in a single layer on the outer surface of the heating cylinder 100, and the entire heating cylinder 100 is hung and fixed at the lower position in the middle of the rear wall 220 of the furnace box (refer to Figure 1). The inner walls of the walls 210 and 220 are close to each other, and the walls 210 and 220 of the incubator are respectively opened with holes 211 and 221 at the corresponding positions of the inner cavity of the heating cylinder, so that the outside world is directly connected with the inner cavity of the heating cylinder 100, but not connected with the inner chamber 205 of the incubator ;

The cooling fan 102 is fixed on the opening of the rear wall 220 of the incubator;

The chromatographic sampler 121 and the chromatographic detector 122 are installed on the top of the chromatographic furnace box, the inlet port 111 of the quartz capillary column is connected to the chromatographic sampler 121, and the outlet port 112 of the capillary column is connected to the chromatographic detector 122;

Three thermistors ( 310 ) Pt100 are respectively fixed on the outer surface of the heating cylinder 100 and the heating blocks of the chromatography sampler 121 and the detector 122 , and are connected with the temperature controller 300 . The temperature controller controls the temperatures of the heating cylinder 100, the chromatographic sampler 121 and the chromatographic detector 122 respectively.

This embodiment is used to separate and analyze various mixed standard samples.

Samples: methanol, acetaldehyde, ethanol, acetone, dichloromethane, n-hexane, chloroform, furan, dichloroethane, benzene, n-butanol, ethylene glycol, trichloroethylene, heptane, toluene, octane, ethyl Benzene, o-xylene, m-xylene, p-xylene, nonane, decane (sample concentration 1000ppm)

Gas chromatography conditions: split/splitless inlet temperature 250°C; FID detector temperature 250°C; 30m×0.25mm×0.5mm MXT-5 column (Restek, USA); carrier gas type: H ₂ , carrier gas flow rate: 1mL/min; split injection, split ratio 50:1, injection volume 1μL; temperature program: keep at 30°C for 8min, then raise the temperature to 175°C at a rate of 10°C/min for 2min. The chromatogram is shown in Figure 4.

Claims (7)

1. A small furnace box without cold zone and low power consumption is characterized in that: the device is composed of heating cylinder (100), heating wire or heating film (101), cooling fan (102), capillary chromatographic column (110), Composed of a chromatographic sampler (121), a chromatographic detector (122), an incubator (200), a temperature controller (300) and a thermistor (310); The heating cylinder (100) is a cylindrical structure with two ends open; the incubator (200) is a closed cavity; A heating wire or a heating film (101) is pasted on the inner wall of the heating cylinder (100), the capillary chromatographic column (110) is wound on the outer surface of the heating cylinder (100), and the inlet end (111) of the capillary chromatographic column is connected to the chromatographic sampling device (121), the capillary chromatographic column outlet end (112) is connected to the chromatographic detector (122), and the two ends of the heating cylinder (100) are connected to the front and rear walls (210) and (220) of the incubator (200). The inner wall is close to the inner wall, and the front and rear walls (210) and (220) of the incubator are respectively provided with a front wall through hole (211) and a rear wall through hole (221) corresponding to the inner cavity of the heating cylinder, so that the outside world and The inner cavity of the heating cylinder (100) is directly connected; The cooling fan (102) is fixed on the opening of the incubator wall (210) or (220); Three thermistors (310) are respectively fixed on the outer surface of the heating cylinder (100) and on the heating blocks of the chromatographic sample injector (121) and the detector (122), and the thermistors (310) and the temperature control The device (300) is connected by a wire; the temperature controller controls the temperature of the heating cylinder (100), the chromatographic sample injector (121) and the chromatographic detector (122) respectively; The heating of the leading end (111) and (112) of the capillary chromatographic column (110) is to rely on the thermal radiation of the chromatographic sample injector (121) and the chromatographic detector (122) and the thermal radiation of the heating cylinder, as well as the thermal radiation of the carrier gas. Realized by heat conduction; Because during normal use, the temperature of the chromatographic sample injector and the chromatographic detector is always higher than the maximum temperature of the capillary chromatographic column, and the temperature of the heating cylinder (100) is always at the relative minimum value of the furnace interior (205), Ensure that the temperature of the capillary column outlet (111) and (112) located below the chromatographic injector and detector is always higher than the temperature of the main body of the capillary chromatographic column; the chromatographic injector (121) and detector ( The distance L between the axes of 122) is greater than the diameter D of the heating cylinder, assuming that the diameter of the metal part of the injector exposed on the top of the furnace is d1, and the diameter of the metal part of the detector exposed on the top of the furnace is d2, then the optimal value of L L=D+d1/2+d2/2, so that the heat radiation area can cover the leading end of the capillary chromatographic column without excessively affecting the corresponding part of the main body of the chromatographic column. 2. The small furnace box according to claim 1, characterized in that: The chromatographic sample injector (121) and the chromatographic detector (122) are installed on the outer wall of the chromatographic furnace incubator, and the chromatographic sample injector (121) and the detector (122) are respectively heated by the heating block provided on it, and the chromatographic The heating blocks of the injector (121) and the detector (122) are both placed in the inner chamber (205) of the chromatographic furnace incubator. 3. The small furnace box according to claim 1, characterized in that: The heating wire or heating film (101), and the heating block of the chromatographic sampler (121) and the detector (122) are respectively connected to the external power supply through the temperature controller (300) through the wire, and the heating cylinder ( 100), the temperature of chromatographic injector (121) and chromatographic detector (122). 4. The small furnace box according to claim 1, characterized in that: the edges of both ends of the heating cylinder (100) are in close contact with the inner walls of the front and rear walls (210) and (220) of the incubator (200) Then, the internal cavity of the heating cylinder (100) is not communicated with the inner chamber of the insulated box (205), that is, the outside world is not connected with the inner chamber of the insulated box (205). 5. The small furnace box according to claim 1, characterized in that: the cooling fan (102) is fixed outside the side wall of the inner chamber of the incubator, and the specific position is the opening in the wall (210) or (220) of the incubator parts. 6. The small-sized furnace box according to claim 1, characterized in that: in the six faces of the inner wall of the furnace chamber of the holding furnace box (200), in addition to being equipped with a chromatographic sampler (121) and a detector (122) Except for the upper part of the furnace, the remaining 5 surfaces are not covered with metal sheets, or are partially covered with metal sheets with a thickness of ≤0.3mm and a mesh with holes, so as to reduce the heat capacity of the furnace, so that the temperature of the furnace can quickly track the temperature of the heating cylinder (100) Heat up or down, but always at a temperature slightly above the heating cartridge. 7. The small furnace box according to claim 1, characterized in that: the heating cylinder (100) is suspended inside the heat preservation box (200).